AUDI A8 1995 D2 / 1.G AEB Engine Motronic MFI And Ignition System

24-29

- Compare display and specified values (display
fields 1 and 2):

Display fields

1 2 3 4
Display group 41: Oxygen Sensor (O2S) heating
Display
xx.x
Htg.bC.ON/Htg.bC.OFF
xx.x
Htg.aC.ON/Htg.aC.OFF
Indicates Resistance of oxygen
sensor heater
(before TWC) O2S heater on
or
O2S heater off
(before TWC) Resistance of oxygen
sensor heater
(after TWC) O2S heater on
or
O2S heater off
(after TWC)
Range
0.0-65.0
--- --- ---
Specified
value 4.9-19.9
Htg.bC.ON --- ---

If not as specified Page 24
-30
, Continuation
--- ---
If displayed values are OK (as specified):

-
Press button to advance program
sequence.
-
Press buttons -0- and -6- to select "End Output"
function 06, and press -Q- button to confirm
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input.

- Switch ignition off.
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24-30

Continuation

- Disconnect 4-pin connector -1- (brown) for
Heated Oxygen Sensor (HO2S) -G39-.

If resistance is NOT OK: - Connect multimeter US 1119 (Fluke 83 or equivalent) between HO2S
connector terminals 1 and 2, using VW 1594 connector test kit.
- Measure resistance.

Specified value: 0.0-19.9 - Replace Heated Oxygen Sensor (HO2S) -G39-.
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24-31
If resistance is OK:

- Switch multimeter to 20 VDC measuring
range.

If display = Htg.bC.ON:
If display switches between "Htg.bC.ON" and "Htg.bC.OFF:" - Connect multimeter between harness connector terminals 1 and 2 (to
ECM), using VW 1594 connector test kit.
- Measure voltage supply and check display in display group 41, display
field 2.
Specified value: 11.0-14.5 volts Specified value: 0.0-12.0 volts (oscillating)
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If there is no voltage:

If there is still no voltage: - Connect multimeter between harness connector terminal 1 (to ECM)
and vehicle Ground, using VW 1594 connector test kit.
Specified value: 11.0-14.5 volts
- Check wiring between terminal 1 and relay panel using appropriate
wiring diagram.
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24-33
If there is voltage:

If display = Htg.bC.ON:
If display switches between "Htg.bC.ON" and "Htg.bC.OFF:" - Connect multimeter between harness connector terminal 2 (to ECM)
and Battery Positive Voltage (B+), using VW 1594 connector test kit.
- Measure voltage supply and check display in display group 41, display
field 2.
Specified value: 11.0-14.5 volts Specified value: 0.0-12.0 volts (oscillating)
- Switch ignition off.
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24-34
If there is no voltage:

- Connect VAG 1598/22 test box to ECM harness
connector Page 01
-56
.

If wiring is OK: - Check wiring for open circuit between ECM/test box and 4-pin HO2S
harness connector (to ECM).

Connector terminal 2 to ECM/test box socket 27
Specified value: max. 1.5
- Replace Motronic ECM -J220- Page 01
-57
- Initiate adaptation of throttle valve control module to ECM Page 24
-
119
.
- Check readiness code Page 01
-59
. If Diagnostic Trouble Code
(DTC) memory has been erased, or ECM was disconnected, generate
new readiness code Page 01
-62
.
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24-35

Oxygen Sensor (O2S) behind Three Way
Catalytic Converter (TWC) and oxygen
sensor control, checking


Notes:

Harness connector for Oxygen Sensor (O2S)
behind Three Way Catalytic Converter (TWC):
4-pin, black
Component locations Page 24
-1

Required special tools and test equipment

VAG 1551 or VAG 1552 Scan Tool (ST) with
VAG 1551/3 adapter cable
VAG 1598/22 test box
Multimeter US 1119 (Fluke 83 or equivalent)
VW 1594 connector test kit
Wiring diagram

Test requirements

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Engine Coolant Temperature (ECT) at least
85 C (185 F)
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24-36

Function test

- Connect VAG 1551 or VAG 1552 scan tool and
press buttons -0- and -1- to insert "Engine
Electronics" address word 01 (with engine
running at idle) Page 01
-7 .
Rapid data transfer
HELP
Select function XX

Indicated on display
- Press buttons -0- and -8- to select "Read Measuring Value Block"
function 08, and press -Q- button to confirm input.
Read Measurin
g Value Block
HELP
Input displa
y group number XXX

Indicated on display
- Press buttons -0-, -3- and -6- to input display group number 36, and
press -Q- button to confirm input.
Read Measuring Value Block 36 1 2 3 4

Indicated on display (1-4 = display fields)
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